Special Condensed Matter Seminar: High performance spintronic devices for microwave technology and computing

Giovanni Finocchio
University of Messina, Messina, Italy
Friday, March 3, 2023
2:30 pm
RH 142


In this talk, I will present recent advances achieved in the development of spintronic microwave detectors,
oscillators and amplifiers based on magnetic tunnel junctions (MTJs). I will review the main applications
of those devices for computing including the realization of Ising machines based on probabilistic
computing with p-bits.
The spintronic technology takes advantage of the manipulation of the electron spin together with its
charge. This technology potentially combines important characteristics such as ultralow power needs,
compactness (nanoscale size) and it is CMOS-compatible. Spintronics has different success stories such
as the head read for magnetic hard drive and the recent spin-transfer-torque magnetic random access
memories. The latter are realized with MTJs which are devices composed by two ferromagnets separated
by a ultrathin isolating material. The resistance of this device depends on the relative orientation of the
magnetization of the two ferromagnets and in particular the configuration where the magnetization are
parallel or antiparallel can code the binary information. Together with memory developments, which are
already in the market and integrated within the CMOS processes by main foundries (INTEL, SAMSUNG,
GlobalFoundries), MTJs can be used for the development of auto-oscillators and very high efficient
detectors. In detail, I will show the applications of spintronic diodes based on MTJs for energy harvesting,
sensors and RF detectors and what it is expected to achieve in the next three years for integration with
CMOS-technology. I will also present, theoretical predictions on how voltage controlled
magnetocrystalline anisotropy (VCMA) can be used to excite linear and parametric resonant modes in
easy-axis antiferromagnetic materials AFMs with perpendicular anisotropy, thus opening the way for an
efficient electrical control of the Néel vector, and for electrical detection of THz dynamics. In particular, I
will focus on two key results: (i) VCMA parametric pumping experiences the so-called “exchange
enhancement” of the coupling efficiency and, thus, is 1-2 orders of magnitude more efficient than
microwave magnetic fields or spin-orbit-torques, and (ii) zero-field parametric resonance, which cannot
be achieved by other parametric pumping mechanisms in AFMs with out-of-plane easy axis.
The latter part of the talk will focus on probabilistic computing which is one direction to implement Ising
Machines. Probabilistic computing is a computational paradigm using probabilistic bits (p-bits), unit in
the middle between standard bit and q-bits. I will show how to map hard combinatorial optimization
problems (Max-Sat, Max-Cut, etc) into Ising machine and how to implement those in spintronic
This work was supported under the project number 101070287 — SWAN-on-chip — HORIZON-CL4-
2021-DIGITAL-EMERGING-01, the project PRIN 2020LWPKH7 funded by the Italian Ministry of
University and Research., and by the PETASPIN association (www.petaspin.com).

Biography of Invited Speaker:
Giovanni Finocchio received the Ph.D. degree in advanced technologies in optoelectronic,
photonic and micromagnetic modeling from the University of Messina, Italy, in 2005. Since
2010, he has been an Assistant Professor first and Associate professor now with the Department
of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences at the University
of Messina. He is director of the laboratory PETASPIN (Petascale computing and Spintronics) at
Messina. His research interests include spintronics, skyrmions, and computing
(https://scholar.google.co.uk/citations?user=eKDbn-oAAAAJ&hl=en). In the last 10 years, he
served on many technical program committees of international conferences and organized more
than 10 international conferences and workshops as Chair, Program Committee Member, or in
other positions. He is regularly invited at conferences in Magnetism and Spintronics. He is also
president of Petaspin association (www.petaspin.com), AdCOM member of the IEEE Magnetics
society, chair of the TC-16 on Quantum, neuromorphic and unconventional computing of the
IEEE Nanotechnology council and past-chair of the IEEE Magnetics Italy chapter (2019-2022).
Since 2022, he is also associate editor of Physical Review Applied (APS).

Ilya Krivorotov